Paternal weight prior to conception and infant birthweight: a prospective cohort study

Multifaceted paternal exposures before conception and their epigenetic impact on offspring

As scientific research progresses, there is an increasing understanding of the importance of paternal epigenetics in influencing the health and developmental path of offspring. Prior to conception, the environmental exposures and lifestyle choices of fathers can significantly influence the epigenetic state of sperm, including DNA methylation and histone changes, among other factors. These alterations in epigenetic patterns have the potential for transgenerational transmission potential and may exert profound effects on the biological characteristics of descendants. Paternal epigenetic changes not only affect the regulation of gene expression patterns in offspring but also increase the risk to certain diseases. It is crucial to comprehend the conditions that fathers are exposed to before conception and the potential outcomes of these conditions. This understanding is essential for assessing personal reproductive decisions and anticipating health risks for future generations. This review article systematically summarizes and analyzes current research findings regarding how paternal pre-pregnancy exposures influence offspring as well as elucidates underlying mechanisms, aiming to provide a comprehensive perspective for an enhanced understanding of the impact that paternal factors have on offspring health.

Effect of Paternal Body Mass Index on In Vitro Fertilization and Neonatal Outcomes among Oligozoospermia and Asthenospermia Patients

PURPOSE

Male overweight and obesity could affect sperm quality and reproductive health. However, the impact of body mass index (BMI) on assisted reproductive technology (ART) outcomes in oligospermia and/or asthenospermia patients is yet lacking. This study aims to assess the impact of paternal BMI on ART and neonatal outcomes among oligozoospermia and/or asthenospermia patients undergoing in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI).

MATERIALS AND METHODS

In this study, 2,075 couples undergoing their first fresh embryo transfer between January 2015 and June 2022 were recruited. Following the World Health Organization's (WHO's) categories, couples were stratified into three cohorts based on paternal BMI: normal weight (18.5-24.9 kg/m²), overweight (25.0-29.9 kg/m²), and obese (≥30.0 kg/m²). Modified Poisson regression models were used to assess the associations of paternal BMI with fertilization, in vitro embryonic development, and pregnancy outcomes. Logistic regression models were performed to investigate the associations of paternal BMI with pregnancy loss and neonatal outcomes. Furthermore, stratified analyses were performed based on fertilization methods, male infertility cause, and maternal BMI.

RESULTS

Higher paternal BMI is associated with a lower likelihood of achieving normal fertilized (p-trend=0.002), Day 3 transferable (p-trend=0.007), and high-quality embryos (p-trend=0.046) in IVF cycles, rather than in ICSI cycles. Paternal BMI of oligospermia or asthenospermia was negatively correlated with day 3 transferable (p-trend=0.013 and 0.030) and high-quality embryos (p-trend=0.024 and 0.027). Moreover, for neonatal outcomes, paternal BMI was positively associated with macrosomia (p-trend=0.019), large for gestational age (LGA) (p-trend=0.031), and very LGA (p-trend=0.045).

CONCLUSIONS

Our data suggested that higher paternal BMI was associated with fetal overgrowth, reduced fertilization, and embryonic development potential. Among males with oligospermia and/or asthenospermia, the impact of overweight and obesity on the choice of fertilization method and the long-term effects on their offspring need to be further investigated.

Paternal preconception modifiable risk factors for adverse pregnancy and offspring outcomes: a review of contemporary evidence from observational studies

BACKGROUND

The preconception period represents transgenerational opportunities to optimize modifiable risk factors associated with both short and long-term adverse health outcomes for women, men, and children. As such, preconception care is recommended to couples during this time to enable them to optimise their health in preparation for pregnancy. Historically, preconception research predominately focuses on maternal modifiable risks and health behaviours associated with pregnancy and offspring outcomes; limited attention has been given to inform paternal preconception health risks and outcomes. This systematic review aims to advance paternal preconception research by synthesising the current evidence on modifiable paternal preconception health behaviours and risk factors to identify associations with pregnancy and/or offspring outcomes.

METHODS

Medline, Embase, Maternity and Infant care, CINAHL, PsycINFO, Scopus, and ISI Proceedings were searched on the 5^th of January 2023, a date limit was set [2012-2023] in each database. A Google Scholar search was also conducted identifying all other relevant papers. Studies were included if they were observational, reporting associations of modifiable risk factors in the preconception period among males (e.g., identified as reproductive partners of pregnant women and/or fathers of offspring for which outcomes were reported) with adverse pregnancy and offspring outcomes. Study quality was assessed using the Newcastle-Ottawa Scale. Exposure and outcome heterogeneity precluded meta-analysis, and results were summarised in tables.

RESULTS

This review identified 56 cohort and nine case control studies. Studies reported on a range of risk factors and/or health behaviours including paternal body composition (n = 25), alcohol intake (n = 6), cannabis use (n = 5), physical activity (n = 2), smoking (n = 20), stress (n = 3) and nutrition (n = 13). Outcomes included fecundability, IVF/ISCI live birth, offspring weight, body composition/BMI, asthma, lung function, leukemia, preterm birth, and behavioural issues. Despite the limited number of studies and substantial heterogeneity in reporting, results of studies assessed as good quality showed that paternal smoking may increase the risk of birth defects and higher paternal BMI was associated with higher offspring birthweight.

CONCLUSION

The current evidence demonstrates a role of paternal preconception health in influencing outcomes related to pregnancy success and offspring health. The evidence is however limited and heterogenous, and further high-quality research is needed to inform clinical preconception care guidelines to support men and couples to prepare for a health pregnancy and child.

Parental pre-pregnancy body mass index and risk of low birth weight in offspring: A prospective cohort study in central China

Background

Low birth weight (LBW) is one of the most common adverse pregnancy outcomes. Previous studies have consistently shown that maternal body mass index (BMI) status before and during pregnancy is associated with LBW. However, previous studies lacked an association between paternal BMI and the conjunction effect of a couple's BMI and LBW in the offspring. Therefore, we established a cohort of pre-pregnancy couples to prospectively assess the relationship between maternal and paternal pre-pregnancy BMI and offspring LBW, very low birth weight (VLBW), and extremely low birth weight (ELBW).

Methods

A prospective cohort study was established in Central China. A total of 34,104 pregnant women with singleton pregnancies at 8-14 gestational weeks and their husbands were finally enrolled and followed to 3 months postpartum. The multivariate logistic regression and restrictive cubic spline model were used to explore the relationship between parental pre-pregnancy BMI and the risk of LBW, VLBW, and ELBW in offspring.

Results

Of the 34,104 participants, maternal pre-pregnancy overweight and obesity were associated with a higher risk of LBW (overweight: OR = 1.720, 95% CI = 1.533 ~ 1.930; obesity: OR = 1.710, 95% CI = 1.360 ~ 2.151), VLBW (overweight: OR = 2.283, 95% CI = 1.839 ~ 2.834; obesity: OR = 4.023, 95% CI = 2.855 ~ 5.670), and ELBW (overweight: OR = 3.292, 95% CI = 2.151 ~ 5.036; obesity: OR = 3.467, 95% CI = 1.481 ~ 8.115), while underweight was associated with a higher risk of LBW (OR = 1.438, 95% CI = 1.294 ~ 1.599) and a lower risk of ELBW (OR = 0.473, 95% CI = 0.236 ~ 0.946). Paternal pre-pregnancy overweight and obesity were associated with a higher risk of LBW (overweight: OR = 1.637, 95% CI = 1.501 ~ 1.784; obesity: OR = 1.454, 95% CI = 1.289 ~ 1.641) and VLBW (overweight: OR = 1.310, 95% CI = 1.097 ~ 1.564; obesity: OR = 1.320, 95% CI = 1.037 ~ 1.681), while underweight was associated with a lower risk of LBW (OR = 0.660, 95% CI = 0.519 ~ 0.839). Parents who were both excessive-weights in pre-pregnancy BMI, as well as overweight mothers and normal-weight fathers before pre-pregnancy, were more likely to have offspring with LBW, VLBW, and ELBW. Dose-response relationship existed between parental pre-pregnancy and LBW, VLBW, and ELBW, except for paternal BMI and ELBW.

Conclusions

Parental pre-pregnancy BMI was associated with the risk of LBW in offspring. Management of weight before pregnancy for couples might help reduce their adverse pregnancy outcomes in future intervention studies.

Association between paternal pre-pregnancy body mass index with preterm birth and low birth weight

Background

With the current global epidemic of obesity, especially among men, there is a need to understand its impact on adverse pregnancy outcomes. This study aimed to assess whether paternal pre-pregnancy body mass index (BMI) was associated with preterm birth and low birth weight in offspring.

Methods

Multinomial logistic regression model was used to analyze associations between paternal BMI and preterm birth and low birth weight in different subgroups, the final model was adjusted for confounding factors of mothers and fathers. Further subgroup analysis was conducted to explore the stability of the risk associations.

Results

A total of 34,104 participants were included in this study, including 1,442 (4.2%) underweight, 13,930 (40.9%) overweight and 5,008 (14.7%) obese according to paternal BMI. The total incidence of preterm birth was 11.85% (4041/34104), and the incidence of low birth weight was 8.86% (3020/34104). In the total study population, compared with normal weight men, paternal pre-pregnancy overweight or obese was associated with a significantly increased risk of preterm birth [aOR; 95% CI respectively (1.34; 1.25-1.45 vs. 1.26; 1.14-1.40)] and low birth weight [aOR; 95% CI respectively (1.60; 1.46-1.74 vs. 1.40; 1.25-1.58)] in offspring. The results of subgroup analysis showed that the direction of the risk association was consistent, indicating good stability.

Conclusion

Paternal pre-pregnancy overweight and obesity were associated with an increased risk of preterm birth and low birth weight in their offspring.

Is birthweight influenced equally by maternal and paternal anthropometry?

OBJECTIVES

To elucidate the influence of parental biometric factors on fetal birthweight (BW).

STUDY DESIGN

This prospective study was conducted between 2015 and 2017 in Hadassah University Hospital. Inclusion criteria included singletons that were born to healthy mothers at 37-41 weeks' gestation and had no growth abnormality or congenital malformation. Maternal and paternal head circumference, weight, and height were measured. Other data including neonatal head circumference and neonatal birthweight were also collected. Neonatal head circumference and birthweight percentiles were converted to sex-specific ranks according to the neonatal Intergrowth 21 charts (rank = 1 for percentile <3, rank = 2 for percentile 3-10, etc.).

RESULTS

One hundred and ninety-nine trios (mother, father, and neonate) were included in the final analysis. In univariate analysis, maternal head circumference (p = .006), maternal height (p = .001), maternal weight before pregnancy (p < .001), maternal weight at term (p < .001), gestational weight gain (p = .009), paternal height (p = .018), neonatal head circumference (p < .001), and neonatal head circumference percentile rank (p < .001) were significant predictors of neonatal birthweight percentile rank. In multivariate regression, the three factors that were significant independent predictors of neonatal birthweight percentile rank were maternal weight before pregnancy (p = .047), maternal weight at term (p = .01), and neonatal head circumference percentile rank (p < .001). No interaction was found between neonatal sex and any of the tested variables. Neonatal sex-specific multivariate analysis showed that maternal height (p = .013), gestational weight gain (p = .005), and neonatal head circumference percentile rank (p < .001) were predictors of birthweight percentile rank in males. Maternal weight at term (p < .001) and neonatal head circumference percentile rank (p < .001) were predictors of birthweight percentile rank in females.

CONCLUSIONS

Maternal height and weight parameters as well as neonatal head circumference percentile rank were found to be independent predictors of birthweight percentile rank. Paternal parameters did not show any significant association in multivariable analysis. The biological regulation of fetal size is assumed to be the result of strong evolutionary selection. As the fetus must pass through the mother's birth canal, there should be a natural match between maternal and fetal size to ensure the successful birth and survival of mother and offspring.

Analysis of Preconception Paternal Smoking and Neonatal Outcomes

This cohort study evaluates the associations of preconception paternal smoking with neonatal outcomes.